Skip to contentSkip to conversation

VDE backend does not handle EINTR properly

uml-devel Frank Laub 2 participants 3 messages Nov 19, 2011 – Nov 20, 2011 User-mode Linux (UML)

lore
Share & tools
lore

Frank Laub

author
#0 lore raw

When running the VDE backend with 2 uml instances and running iperf between them, the vde_send() function often returns EINTR. I noticed that this is accounted for in net_user.c via the use of the CATCH_EINTR() macro. Thus the following patch uses the same approach for calls into VDE. It could be argued that the VDE library itself should handle EINTR, but this patch will work with older (or current) versions of VDE. This patch was created against 3.0.3.

arch/um/drivers/vde_user.c +12 -2
@@ -11,6 +11,7 @@
  #include "um_malloc.h"
  #include "user.h"
  #include "vde.h"
+#include "os.h"
 
  static int vde_user_init(void *data, void *dev)
  {

@@ -103,7 +104,7 @@ int vde_user_read(void *conn, void *buf,
      if (vconn == NULL)
          return 0;
 
-    rv = vde_recv(vconn, buf, len, 0);
+    CATCH_EINTR(rv = vde_recv(vconn, buf, len, 0));
      if (rv < 0) {
          if (errno == EAGAIN)
              return 0;

@@ -118,10 +119,19 @@ int vde_user_read(void *conn, void *buf,
  int vde_user_write(void *conn, void *buf, int len)
  {
      VDECONN *vconn = conn;
+    int rv;
 
      if (vconn == NULL)
          return 0;
 
-    return vde_send(vconn, buf, len, 0);
+    CATCH_EINTR(rv = vde_send(vconn, buf, len, 0));
+    if (rv < 0) {
+        if (errno == EAGAIN)
+            return 0;
+        return -errno;
+    }
+    else if (rv == 0)
+        return -ENOTCONN;
+    return rv;
  }

------------------------------------------------------------------------------
All the data continuously generated in your IT infrastructure contains a definitive record of customers, application performance, security threats, fraudulent activity, and more. Splunk takes this data and makes sense of it. IT sense. And common sense.
http://p.sf.net/sfu/splunk-novd2d
_______________________________________________
User-mode-linux-devel mailing list [email protected]
https://lists.sourceforge.net/lists/listinfo/user-mode-linux-devel

#1 lore raw

Am 20.11.2011 00:16, schrieb Frank Laub:

Quoted 7 lines

When running the VDE backend with 2 uml instances and running iperf between them, the vde_send() function often returns EINTR. I noticed that this is accounted for in net_user.c via the use of the CATCH_EINTR() macro. Thus the following patch uses the same approach for calls into VDE. It could be argued that the VDE library itself should handle EINTR, but this patch will work with older (or current) versions of VDE. This patch was created against 3.0.3.

Please add a Signed-off-by tag,
so that I can give you the credit. :-)
See: http://linux.yyz.us/patch-format.html

Quoted 20 lines
arch/um/drivers/vde_user.c +2 -1
@@ -11,6 +11,7 @@
  #include "um_malloc.h"
  #include "user.h"
  #include "vde.h"
+#include "os.h"
 
  static int vde_user_init(void *data, void *dev)
  {

@@ -103,7 +104,7 @@ int vde_user_read(void *conn, void *buf,
      if (vconn == NULL)
          return 0;
 
-    rv = vde_recv(vconn, buf, len, 0);
+    CATCH_EINTR(rv = vde_recv(vconn, buf, len, 0));
      if (rv < 0) {
          if (errno == EAGAIN)
              return 0;

arch/um/drivers/vde_user.c int vde_user_read(void *conn, void *buf, · line 125

Quoted 9 lines
arch/um/drivers/vde_user.c +1 -1
@@ -118,10 +119,19 @@ int vde_user_read(void *conn, void *buf,
  int vde_user_write(void *conn, void *buf, int len)
  {
      VDECONN *vconn = conn;
+    int rv;
 
      if (vconn == NULL)
          return 0;
 
-    return vde_send(vconn, buf, len, 0);

Is the additional if-branch really needed?

arch/um/drivers/vde_user.c int vde_user_read(void *conn, void *buf, · line 137

Quoted 11 lines
arch/um/drivers/vde_user.c +9 -0
+    CATCH_EINTR(rv = vde_send(vconn, buf, len, 0));
+    if (rv < 0) {
+        if (errno == EAGAIN)
+            return 0;
+        return -errno;
+    }
+    else if (rv == 0)
+        return -ENOTCONN;
+    return rv;
  }

Thanks,
//richard

------------------------------------------------------------------------------
All the data continuously generated in your IT infrastructure contains a definitive record of customers, application performance, security threats, fraudulent activity, and more. Splunk takes this data and makes sense of it. IT sense. And common sense.
http://p.sf.net/sfu/splunk-novd2d
_______________________________________________
User-mode-linux-devel mailing list [email protected]
https://lists.sourceforge.net/lists/listinfo/user-mode-linux-devel

author
#2 lore raw

Re: [uml-devel] ]PATCH 3.03 1/1] um: VDE backend needs to handle EINTR/EAGAIN

Handle EINTR and EAGAIN during vde_send() and vde_recv() in case the VDE library doesn't. Use the same approach that net_user.c takes.

Signed-off-by Frank Laub<[email protected]>
arch/um/drivers/vde_user.c +10 -2
@@ -11,6 +11,7 @@
  #include "um_malloc.h"
  #include "user.h"
  #include "vde.h"
+#include "os.h"
 
  static int vde_user_init(void *data, void *dev)
  {

@@ -103,7 +104,7 @@ int vde_user_read(void *conn, void *buf,
      if (vconn == NULL)
          return 0;
 
-    rv = vde_recv(vconn, buf, len, 0);
+    CATCH_EINTR(rv = vde_recv(vconn, buf, len, 0));
      if (rv < 0) {
          if (errno == EAGAIN)
              return 0;

@@ -118,10 +119,17 @@ int vde_user_read(void *conn, void *buf,
  int vde_user_write(void *conn, void *buf, int len)
  {
      VDECONN *vconn = conn;
+    int rv;
 
      if (vconn == NULL)
          return 0;
 
-    return vde_send(vconn, buf, len, 0);
+    CATCH_EINTR(rv = vde_send(vconn, buf, len, 0));
+    if (rv < 0) {
+        if (errno == EAGAIN)
+            return 0;
+        return -errno;
+    }
+    return rv;
  }

------------------------------------------------------------------------------
All the data continuously generated in your IT infrastructure contains a definitive record of customers, application performance, security threats, fraudulent activity, and more. Splunk takes this data and makes sense of it. IT sense. And common sense.
http://p.sf.net/sfu/splunk-novd2d
_______________________________________________
User-mode-linux-devel mailing list [email protected]
https://lists.sourceforge.net/lists/listinfo/user-mode-linux-devel